For example, Patent Document 1 discloses a light emitting apparatus which has a plurality of light emitting diodes mounted on a metal substrate.
In a conventional light emitting apparatus, a surface of a metal substrate is covered with a resin insulating layer. First and second conductive portions are provided on the insulating layer. The first conductive portion and the second conducive portion are separated by a slit and electrically insulated from each other. Back surfaces of the light emitting diodes are electrically connected to the first conductive portion. Front surfaces of the light emitting diodes are electrically connected to the second conductive portion through bonding wires.
Furthermore, the light emitting diodes are covered with a transparent sealing resin. The sealing resin continuously covers the first conductive portion, the second conductive portion, and the bonding wires.
According to the conventional light emitting apparatus, surfaces of the first and second conductive portions are covered with a metal film having oxidation resistance such as Ni or Au. A surface of this type of metal film can be maintained as a mirror finished surface, and hence the first and second conductive portions can be utilized as reflecting plates. Moreover, since the metal film is hardly oxidized, it does not lose specularity even if it is exposed to an oxidizing atmosphere.
Therefore, light traveling from the light emitting diodes to the metal substrate can be effectively reflected at positions of the first and second conductive portions toward a light fetching direction.